[MP] Rend2: rend2 is now up to date through ioq3 rend2 commits.

Latest being "OpenGL2: Add normalScale and parallaxDepth stage keywords and helper cvars."
[MP] Restore old currentVM with non legacy API.
[MP] Also fix an earlier crash in /give <item> if removed in G_SpawnItem and not just in FinishSpawningItem.
[MP] Remove assigned-but-not-used `lastVM` variable.
[MP] Some AI bugs (OVERFLOW!) in the bot movement code.
From Tobias Kuehnhammer in ioq3 commit: ioquake/ioq3@eb9fe030c47281e6145908e0331cc543b4aaf432
[MP] Rend2: Always add minimum light to be like vanilla.
Might make some refents like players and models a bit brighter than before when hdr was on.
[MP] Remove unused function prototype
[MP/SP] Use callbackFunc_t
Merge pull request #499 from mike-pm/master

[MP/SP] Code maintenance
[MP] Fixed issue with ENTITYNUM_NONE.
[MP] Allow g_debugDamage cvar in all builds.
[MP] Fix a few gcc warnings in server demo code
JK2 version is now a separate executable, openjo_sp.
JK2 renderer is now separate, rdjosp-vanilla.
Changed __NO_JK2 to JK2_MODE (negated).
jk2game renamed to jospgame since we're not binary compatible anyway.
com_jk2 defaults to 1 in JK2 mode.
Added option to not build renderers.
Got rid of com_jk2 since that's a separate executable now.
Introduce pool allocator for scheduled efx

Before this commit, efx were scheduled to be played by dynamically
allocating memory every time, and then freed when the efx's life time had
ended. Introducing a pool allocator potentially removes the overhead of
many dynamic allocations per frame.

Further work needs to be done to remove dynamic allocations for the
effects themselves (see FX_AddLine, FX_AddBezier, etc. functions).
Merge pull request #506 from mrwonko/jk2-clean

JK2 support in separate executable/library; option to compile renderers
Enabling C++11 in JK2 SP Game Library on GCC/Clang (I think)
Fixed fix being to wrong file
Adjusted Homepath, Product Name & Window Title in JK2 Mode
Merge branch 'master' of github.com:Razish/OpenJK